Handfish live off the coast of Australia, primarily in the shallow, inshore waters around Tasmania. There are 14 species of this fish, nine of which were identified in 2009. They get their name from their unusual method of moving through the water. Instead of swimming like a regular fish, these fish "walk" along the sea floor, using their fins as hands — or feet, as the case may be.
The fins of these fish look hand-like, because the fins are adapted for use in walking instead of swimming. Their dorsal fins may also appear prominent, especially just behind the head, as an adaptation suited to the fish's unusual ecological niche. Different species come in various colors, from pale with yellow fins, to pink, to bright red. Some species have smooth skin and some have wart-like skin. The fish have small, thin protrusions above their mouths like an anglerfish's lure, which is why handfish are also known as warty anglerfish.
These fish make up the family Brachionichthyidae. This family contains five genera, three of which were first described in 2009. The new genera are Brachiopsilus, Pezichthys and Thymichthys; the previously recognized genera are Brachionichthys and Sympterichthys.
A significant amount of information about handfish is derived from observation of the fish in captivity. During the spawning season, for example, the male and female fish create displays for each other through fin and body movements. The male fertilizes the female's eggs externally.
The female spotted handfish and the female red handfish lay from 80 to 250 eggs around a flexible vertical object in the water. For the spotted handfish, this is commonly a stalked sea squirt and, for the red handfish, this is generally algae. The eggs are guarded by the mother fish for up to eight weeks before hatching into fully formed juvenile fish. These juveniles then fall to the sea floor from their egg. The juveniles take several years to mature into fully grown adults.
The habitat for these animals is very specialized, as they are only suited for certain type of marine environments. They are vulnerable to extinction by local environmental disruption and some species are endangered. The fossil record indicates they were much more prevalent in the past Australian marine habitat than they are in the early 21st century.
The Brachionichthyidae family has not been extensively studied. Only four specimens of the 4-inch (10-cm) long pink handfish had been found by early 2011, and these were all found before the year 2000. The behavior and biology of these fish are, therefore, not very well known.